Human skin color is determined according to amounts of melanin, carotene, and hemoglobin, and from among them, melanin acts as the most determining factor. Melanin pigment is a phenol-based polymer material that has a composite form of black pigment and protein, and blocks ultraviolet light, and people who lacks melanin pigment is very sensitive to sun light and is highly likely to have burns, and even at young ages, the possibility of skin cancer is high. Generally, short-wave ultraviolet light and carcinogen form a free radical that is harmful for skin. Melanin removes the free radical to protect proteins and genes. Accordingly, the wording that melanin is present in great quintiles means that an effective response system for the protection of skin from physical or chemical toxicity materials is provided.
Melanin has a circulating cycle: melanin is generated from tyrosine due to an action of tyrosinase in pigment cells through complicated processes, the generated melanin is transferred to skin cells and consumed and removed when excoriation occurs. This melanin generation process naturally occurs, and in a normal-state skin, excess melanin is not generated. However, when skin responses to external stimuli, for example, ultraviolet light, environmental pollution, or stress, excess melanin is generated so that melanin is not discharged into outside the skin but is transferred to keratinocyte to accumulate in a skin epidermis, thereby causing serious cosmetic problems, such as melasma, freckle, and senile lentigo, promoting skin aging, and inducing skin cancer.
Meanwhile, research into the prevention of melanin pigmentation in skin has been performed in four aspects. First, a tyrosinase synthesis inhibiting material or an antagonist against a matrix of tyrosinase is developed to control the activity of tyrosinase, which is an apoenzyme for melanin synthesis. Second, a material that has toxicity to melanocyte, in which melanin biosynthesis occurs in animals, is developed to decrease the function of melanocyte. Third, a material that reduces dopa, which is an intermediate metabolic material of a melanin synthesis path, is developed to prevent the oxidation of dopa. Finally, an activity of a first enzyme tyrosinase, which is a melanin generator, an activity of a second enzyme DOPA chrome tautomerase that promotes conversion from DOPA chrome to 5,6-dihydroxyindole-2-carboxylc acid (DHICA), and an activity of a third enzyme that promotes conversion from DHICA to indole-5,6-quinone-2-carboxylic acid are simultaneously reduced.
Recently, women in the Asia region desire to have skin that is as white and clean as white porcelain, and regard the whiteness and cleanness as critical criteria for the evaluation of beauty. Accordingly, the development of whitening agents for the treatment of abnormal skin pigmentation and the satisfaction of cosmetic desires is actively being performed.
As a known method of developing a whitening agent, there are a decoloration method performed by reducing a generated melanin pigment and a method of suppressing activities of tyrosinase, which is an enzyme for forming melanin pigment. However, a whitening agent prepared by using tocopherol or vitamins to reduce melanin pigment is known to have very small decoloration effects. Accordingly, an inhibitor that suppresses the generation of melanin pigment by inhibiting activities of tyrosinase is getting attention.
In conventional cosmetic fields, as a whitening material, for example, a material for suppressing activities of tyrosinase enzyme, such as kojic acid or arbutin, hydroquinone, vitamin C (L-Ascorbic acid) and a derivative thereof, and various plant extracts are used. However, use of these materials is limited due to their low stability in a prescription system, leading to decomposition and pigmentation, generation of offensive odor, uncertainty and stability of efficacy and effectiveness at bio-levels. Also, although kojic acid allows a copper ion present in an active site of tyrosinase to adsorb to inhibit enzymatic activities, when mixed in cosmetic products, instability, skin adverse effects, and liver cancer, which was recently identified based on animal tests, may occur, and accordingly, use of the kojic acid in cosmetic products was stopped. Vitamin C and a derivative thereof are highly likely oxidized, and due to this instability, it is difficult for these materials to be used in cosmetic source materials. Hydroquinone has excellent skin whitening effects. However, it has high skin irritation because hydroquinone causes allergy, has toxicity to melanin forming cells, and induces permanent decoloration of skin. Also, in many countries, hydroquinone is defined as carcinogen, and thus, only limited concentration of thereof is allowed for use. Arbutin is a derivative in which gucopyranoside binds to hydroquinone, and has smaller adverse effects than when hydroquinone is used, and suppresses synthesis of a melanin pigment without toxicity to human body. Due to such characteristics, its use for the treatment of skin disorders, in which melanin pigmentation more occurs, has been suggested. However, arbutin partly decomposes by skin enzyme. Accordingly, there is a need to develop an alternative whitening agent that has high efficiency even at small concentrations, smaller adverse effects, and stability.
Also, reactive oxygen species (ROS) refers to an in vivo toxic material associated with oxygen, and examples of ROS are a free radical, such as superoxide, hydroxyl, peroxyl, alkoxyl, or hydroperoxyl, and a non-free radical, such as hydrogen peroxide, hypochlorous acid, ozone, singlet oxygen, or peroxynitrite.
From among these ROS, regarding oxygen toxicity, a superoxide free radical (reactive oxygen or harmful oxygen) is the most frequently researched thereinto and plays a critical role (Fridorich L., Science, 201, pp 175-180, 1978). A free radical, which is a strong oxidizing gent, is an unpaired electron. A free radical is generated during oxidation and reduction reactions of various organisms, and may cause deterioration of eatable oil, or may oxidatively damage on various biomaterials (lipid, protein, nucleic acid, carbohydrate) and through various steps, ultimately, mutants may occur (Yen G C et al., J. Agric. Food Chem., 43, pp 27-32, 1995). Regarding an unsaturated fatty acid of phosphatide which constitutes a biological membrane, a free radical, such as reactive oxygen species, initiates a peroxidative reaction and also the reaction is proceeds consecutively. Accordingly, a peroxidative reaction due to the free radical may increase permeability of a cell membrane and cause overall cytotoxicity, thereby inducing aging or pathological phenomenon of aging-associated disorders to be engaged in cancer generation process. The action of a radical heavily affects progress of various chronic disease, such as atopic disease, cancer, hypertension, myocardial infarction, arteriosclerosis, rheumatis, cataract, Parkinson's disease, which are disorders associated with oxidative stress (DeSouza L C et al., Bioorg. Med. Chem. Lett., 14, pp 5859-5861, 2004), and may weaken the function of an immune system (Pike J et al., Int. J. Vitam. Nutr. Res., 65, pp 117-120, 1995).
Accordingly, anti-oxidation evaluation on an alternative material for the prevention from the oxidative damage is very actively performed. Antioxidants do not remove or absorb oxygen, but react with a free radical so that loss of particular vitamins and necessary amino acids is minimized, and corruption of oil product is delayed or prevented. As a synthesis antioxidant used in foods and medical products, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl galate (PG), and tertiary-butyl hydroquinone (TBHQ) may be used. However, when these antioxidants are administered at high concentrations into test animals, hepatomegaly or cancer may progress. In particular, butylated hydroxytoluene is known to, based on various study results, increase enzymatic activity (microsomal enzyme activity in the liver of lab animals), and thus, stability of these phenol-based synthesis antioxidants is debated, and currently, available amounts thereof are legally limited (Brannen A L, J. Amer. Oil Chem. Soc., 52, pp 59-63, 1975; Ito N et al., J. Natl. Cancer Inst., 70, p 343, 1983; Chan K M et al., J. Food. Sci., 58, pp 1-4, 1993). In response, much research into vegetable-originated natural antioxidants that have high antioxidant effects, are stable, and are prepared at low costs is being performed (Larson R A, Phytochemistry, 27, pp 969-978, 1988). Alongside the recent research into natural materials, secondary metabolite that is included in natural materials is getting attention as a bioactive material, and in particular, research into antioxidants is actively being performed, and examples of known natural antioxidants are tocopherols, flavonoids, gossypols, sesamols, oryzanol, and vitamin C (Huson B et al., Food Chem., 19, pp 537-541, 1987; Frankel, E. N. Food Chem., 57, p 51, 1996; Giese J, Food Technol., 5, pp 73-81, 1996; Pszcczola D E, Food Tech., 55, pp 51-59, 2001). In particular, tocopherol and L-ascorbic acid are preferred as a natural antioxidant, and despite its high stability, when used alone, tocopherol has a low oxidation prevention ability (Halliwell B et al., FASEB J., 2, pp 2867-2870, 1988) and is expensive.
Meanwhile, peroxisome is one of intracellular organelles which cause abnormal metabolism functions, and plays a critical role in metabolism of oxygen, glucose, lipid, and hormone, and widely affects controlling of cell proliferation and differentiation, and inflammatory mediators. Also, peroxisome affects, through lipid metabolism and glucose metabolism, insulin sensitivity, the formation of a cell membrane and mast cells, and oxidative stress, thereby playing a critical role in aging and tumorigenesis. Peroxisome proliferator-activated receptor (PPAR) is one of nuclear receptors that control the expression of gene due to a ligand binding, and various fatty acids act as an endogenous ligand. Up to now, three PPAR are known: a peroxisome proliferator-activated receptor alpha (PPARα), a peroxisome proliferator-activated receptor beta (PPARβ/δ), and a peroxisome proliferator-activated receptor gamma (PPARγ)
PPARα generally exists in blood vessel walls, the liver, the heart, muscle, kidney, and brown adipose tissues, and together with fibrates, which is an agonist, PPARα prevents or delays progress of arteriosclerosis, promotes oxidizing fat to prevent obesity. PPARβ or PPARδ generally exists skin, brain or adipose tissues, is engaged in cholestrol antiport, myelination, and cut recovery, and acts as a controller for fatty acid metabolism and energy homestasis. PPARγ generally exists in adipose tissues, and also in blood vessel endodermis, macrophage, and β cells of pancreas, and controls differentiation of adipocytes and plays a critical role in body lipid homestasis. A compound prepared by completely or incompletely activating PPARγ suppresses differentiation of adipocyte to effectively treat obesity, and the incompletely activated compound is effective for the treatment of hyperglycemia as well as obesity. As described above, to prevent and treat a variety of disease that is controlled by an action of PPAR, there is a need to develop a novel compound to effectively control activities of PPAR.